Fasteners such as nails and staples are commonly used in projects ranging from crafts to building construction. While manually driving such fasteners into a work piece is effective, a user may quickly become fatigued when involved in projects requiring a large number of fasteners and/or large fasteners to be driven into a work piece. Moreover, proper driving of larger fasteners into a work piece frequently requires more than a single impact from a manual tool.
In response to the shortcomings of manual driving tools, power-assisted devices for driving fasteners into work pieces have been developed. Contractors and homeowners commonly use such devices for driving fasteners ranging from brad nails used in small projects to common nails which are used in framing and other construction projects. Compressed air has been traditionally used to provide power for the power-assisted (pneumatic) devices.
Various safety features have been incorporated into pneumatic and other power nailers. One such device is commonly referred to as a work contact element (WCE). A WCE is incorporated into nailer designs to prevent unintentional firing of the nailer. A WCE is typically a spring loaded mechanism which extends forwardly of the portion of the nailer from which a nail is driven. In operation, the leading side surface, or contact surface of the WCE is pressed against a work piece into which a nail is to be driven. As the WCE is pressed against the work piece, the WCE compresses the spring and generates an axial movement which is transmitted to a trigger assembly. The axial movement is used to reconfigure a safety device, also referred to as a trigger enabling/disabling mechanism, so as to enable initiation of a firing sequence with the trigger of the nailer.
Nailers may be used for many different jobs. One particular type of job where nailers have found widespread use is in the installation of roofing materials, such as asphalt shingles. Asphalt shingles are a very abrasive material due to the granules of stone that are on the surface of the shingles. Repeated contact between the contact surface of the work contact element and the shingles may cause wear to the contact surface. Due to the potential for wear during roofing applications, some previously known nailers have incorporated wear resistant inserts into the contact surface of the work contact element. The previously known inserts were typically round inserts positioned on opposing sides of the ejection orifice in the work contact element and protruding from the contact surface to contact the abrasive surface of the shingles so as to limit contact between the contact surface and the shingles.
Other surfaces of the WCE may also be susceptible to wear during the installation of shingles. For example, the fastener driving tool may be provided with a shingle gauge assembly to aid in the uniform spacing of shingles. The shingle gauge includes an alignment surface that is substantially parallel to an upper trailing side of the WCE that may be used to control the distance that a fastener is placed into a shingle from the edge of the shingle. During use, the alignment edge of the shingle gauge is lined up with a previously installed shingle. The upper trailing side surface of the WCE may then be used to line up the next row of shingles. This action causes the trailing side surface of the WCE to be pressed and rubbed against the narrow edge of shingles which may result in wear on the trailing side front surface of the work contact element.
One method that may be used to prevent or limit wear to the trailing side surface of the WCE is to add additional inserts that protrude from the trailing side surface to contact the narrow edge of shingles during the alignment process discussed above with regard to the shingle gauge. However, adding additional inserts to the WCE may increase the complexity and cost of manufacturing of the work contact element and have a negative impact on the structural integrity of the WCE.